1. Field of the Invention
The present invention relates to a driving apparatus including a driving unit, and more particularly, to a driving apparatus capable of detecting a position, a camera platform and a lens apparatus including the driving apparatus, and a method of controlling the driving apparatus.
2. Description of the Related Art
Conventionally, there is known an apparatus that performs open-loop control without a position detection function, such as an encoder or a potentiometer, to achieve cost reduction. In particular, there is known an apparatus that performs the open-loop control basically but has a simplified position detection mechanism in order to recognize a reference point, as exemplified by a printer and a monitoring camera.
For instance, Japanese Patent No. 3484289 discloses an example of a printer head in which translucent portions and light-blocking portions are alternately arranged with predetermined widths in a center scaling portion and are arranged in an end portion and a reference position portion with widths different from the widths in the scaling portion, so as to detect the end and the reference position. In addition, Japanese Patent Application Laid-Open No. 2009-65298 discloses an example of a lens barrel rotation type image pickup apparatus that detects an end and rotation, in which light-blocking portions and translucent portions are alternately arranged at a constant interval in a rotation detection portion and are formed at an end portion in a different shape from that in the rotation detection portion.
However, in the conventional technology disclosed in Japanese Patent No. 3484289, the scaling portion is formed like a constant fine scale, and hence the current position cannot be grasped by the scaling portion. Therefore, in order to detect the reference position, it is necessary to drive in the entire region at most, and there is a problem that it takes much time to detect the reference position. Further, if the position is lost once, for example, in a case where the printer head is driven by an external force or a case where noise is applied to an optical sensor, a correct position cannot be grasped unless drive to the reference position is performed, and hence there is a problem that it takes much time to reset the position. The conventional technology disclosed in Japanese Patent Application Laid-Open No. 2009-65298 also has the problem that it takes much time to detect the reference position in an initialization process similarly to the case of Japanese Patent No. 3484289.